The terrain type of a province is shown in the bottom left when selecting it. When provinces visually contain multiple terrain types, the most dominant one is used. All terrain effects except movement cost are based on it.

A path between two adjacent provinces is the straight line between their centers. It is traced on a pixel grid, making diagonal lines noticeably longer than north-south and east-west lines. The terrain along this path (along with its distance) determines its movement cost. The path may consist of the source and target province's terrain in varying proportions or even different terrains altogether. For example the path between two coastal mountain provinces at a fjord might consist of 40% mountain and 60% ocean, resulting in +40% movement cost for this path instead of +100% in a pure mountain range.

The path also determines whether direction-dependent terrain features apply.

This section may contain outdated information that is inaccurate for the current version of the game. The last version it was verified as up to date for was 1.5.

Terrain features can apply adjusters and modifiers in addition to the base terrain. They stack multiplicatively with base terrain values. They only affect the attacker because some of them depend on the path and the defender might fight against attackers from different directions. The attack adjuster applies to the attacker's soft/hard attack and the defense adjuster to their breakthrough.

Small river:-30% to attack/defense and -25% to movement.

Large river:-60% to attack/defense and -50% to movement.

Amphibious landing:-70% to attack/defense.

Fort:-15% to attack/defense per level.

The river adjuster apply when a path intersects a river. If a river modifier is applied in combat, this also allows other battle tactics. The amphibious landing penalty applies when a unit attacks a land province from a sea province. The movement cost of an amphibious landing is a fixed length. The fort adjuster applies in all directions but with each flanking attack the bonus gets diminished.

This section may contain outdated information that is inaccurate for the current version of the game. The last version it was verified as up to date for was 1.5.

Units may have specific adjusters in addition to the base terrain and terrain feature adjusters. The net adjuster for a division is the average of its combat battalions, plus the sum of the adjusters of its support battalions. Among the regular terrain adjusters, the attack value modifies the attacker's attack and breakthrough, and the defense value modifies the defender's attack and defense. For terrain feature adjusters (except amphibious and forts), the attack value modifies the attacker's attack, and the defense value modifies the attacker's breakthrough. The amphibious and fort adjusters ignore their defense value[1] and use the attack value for both attack and breakthrough. The unit's adjuster stacks additively with the terrain and terrain feature adjuster respectively. Divisions lacking manpower have proportionately smaller bonuses and penalties.